A tangent is drawn to the ellipse <img alt="\mathrm{\frac{x^{2}}{a^{2}}+\frac{y^{2}}{b^{2}}=1}" src="https://entrancecorner.oncodecogs.com/gif.latex?%5Cmathrm%7B%5Cfrac%7Bx%5E%7B2%7D%7D%7Ba%5E%7B2%
A tangent is drawn to the ellipse at point uch that it intersect the auxiliary circle at points A and B, if and are the focii of the ellipse, then the minimum value of is